Recently, there has been developed an electronic key system that enables, without being inserted, to lock/unlock a door of an automobile, to start/stop an engine, and the like.
As such an electronic key system, there has been disclosed a biometric authentication key system, for ensuring security, with which a removable data storage device to store biometric information of a registrant as registration information is set in an automobile body and locking/unlocking of a door and driving of the automobile can be performed when biometric information obtained from an occupant for the automobile matches the registration data (e.g., see Patent Literature 1).